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How Cold Weather Impacts Your Concrete Pour

09 Oct 2019, Posted by F.A. in Concrete Facts

Pouring concrete can be a simple task or a difficult one considering both the natural and man-made hurdles the process brings. It all depends on the location, the scope of the project, and the weather.

Unfortunately, the weather often makes getting the perfect concrete pour difficult, especially in northern areas during the late fall, winter, and even early spring. You may find yourself removing the concrete wall forms only to find the concrete behind them is a mess.

Let’s take a look at how cold weather can affect your concrete pours and what you can do about it.

The Concrete Can Easily Freeze

If the temperature is under 40 degrees Fahrenheit, it’s possible that your concrete could freeze. This means that you may need to apply heat to the concrete to help it set.

If you allow the concrete to freeze, thaw, and then set, it’s likely to be weaker than necessary. It may also crack. Always check the temperature, and if there’s any chance that it will drop below 25 degrees Fahrenheit, don’t pour the concrete. It will undoubtedly freeze.

Have a Flexible Schedule

In the warmer months, you may schedule concrete pours on a certain day without any problem, but during the winter, you need to be a little more flexible. You will need to watch the weather and, if necessary, delay the pour by a few days.

In some areas, you may even have to delay it a week or more if you miss the warmer days or if the temperature drops unexpectedly. This can cause significant delays in a project, but unfortunately, that’s often the only option.

Check the Sub-Base

When your sub-base freezes, you will have to wait to pour the concrete. This space needs to be fully thawed because if it’s not, it will contract when it warms up, causing the concrete to crack.

If you’re pouring concrete in the winter, one thing you can do is cover the sub-base with an insulated blanket or other means of protecting it from freezing. Ground heaters can also be used to thaw the area before you pour.

Another issue with the sub-base is that it can pull the heat from the concrete very quickly if it’s cold or frozen. Both pouring on a dirt sub-base or on a sub-base that has a plastic vapor barrier on top of it can cause this issue if the temperature is below 30 degrees.

On the other hand, a sub-base with Styrofoam will not draw out the heat as quickly, which means you can pour the concrete onto this type of sub-base even if it’s as cold as 26.

Have Heaters on Hand

Even if it’s above 30 degrees, it’s always a good idea to have a heater on hand. This may be needed to help heat and thaw the sub-base, but it can also be needed to keep you and your crew warm while you’re pouring the concrete. Working out in the cold all day is going to take its toll on everyone involved, so it’s always nice to be able to create a warm break area.

Troweling the Concrete

It can take as long as five hours for the concrete to set enough so that you can start troweling—it all depends on the mix, the accelerator, and the temperature. Once it does, though, you can trowel it smooth.

The challenge following this is keeping the concrete from freezing until it fully sets. The best solution is, again, insulated blankets. You can also lay a tarp over the surface of the concrete and cover it with hay.

Heated enclosures are another option, but they may require running electrical cords across the work site, which can present a tripping hazard.

Need Forms?

Forming America offers all of the concrete forms and shoring equipment you’ll need for any job, regardless of what the temperature is. If you’re in need of additional concrete forms, contact us today to discuss how we can help you.